NORDIC (North Western Obstructive and Respiratory Disease Investigation Center) proposes to study the obstructive pulmonary syndrome (OPS) and the respiratory distress syndromes (RDS) of the infant and adult. The two sections of the center will be related through their control studies of the normal lung and the normal changes which take place with aging. The OPS section will endeavour to test different parts of a hypothesis about the pathogenesis of OPS through a number of interrelated projects. Each project will itself be staged as far as possible so that data from other projects may be used when appropriate. Where we can, we shall try to assess the clinical relevance of the individual projects by testing them first on simple animal models and then, perhaps, on primates. Similarly, the RDS section is made up of projects which will try to test our hypotheses about the possible cause and progress of infant and adult RDS. Like the OPS study, we shall try and stage these projects and relate them to the clinical syndromes which will themselves be the subject of investigation. The particular emphasis of this center will be on the tissue property changes found in OPS and the metabolic lung abnormalities underlying RDS.